Rapid developments in medical technology in the 1990s have led to the development of a number of computerized devices for identifying the fertile window in the menstrual cycle. Such devices may be a useful adjunct to natural family planning to clarify a difficulty in interpreting the mucus symptom or the basal body temperature (BBT) chart, or as a teaching aid to help identify the fertile phase. The use of such devices may increase the confidence of the NFP user in her own observations of the limits of the fertile phase.
Can these devices be used instead of learning natural family planning and charting the cycle?
The Natural Family Planning Teachers’ Association of Ireland recommend that these devices should not be used alone, but should only be used as an adjunct with the symptothermal double-check method of natural family planning taught by a qualified NFP teacher.
NOTE: Can all these devices be used to avoid pregnancy?
The answer is No. The ‘LH Dipsticks’ are designed to be used by women who are planning to achieve pregnancy and not for those who wish to avoid pregnancy. (see paragraph B (iii) below)
TYPES OF DEVICES:
- Temperature computers.
- Hormonal computers to detect hormone levels in the urine.
- Saliva Tests to assess the ferning pattern, or to determine salivary b-glucuronidase. Tests on saliva are unreliable methods of indicating ovarian activity, and will therefore not be discussed in this text.1,4
TEMPERATURE COMPUTERS:
Temperature computers are devices using computer programs based on the basal body temperature (BBT) method, and the calculation rule. Computerised thermometer such as ‘Bioself 2000′, is a battery-operated electronic thermometer which by means of a micro-chip uses the calendar calculations to detect the onset of the fertile phase, and the shift of BBT to determine the end of the fertile phase in the cycle. ‘Ladycomp/Ladycomp’, ‘cyclotest 2 plus’ are similar devices.
HORMONAL COMPUTERS:
Hormonal computers read the colour signals of dipsticks which measure metabolites of luteinizing hormone (LH), oestrogen, or progesterone in urine either alone or in various combinations. Such devices include those which measure:
(i) Oestradiol and the LH surge :
Persona is a personal hormone monitor which consists of a hand held monitor and disposable test sticks which measure changes in concentrations of oestrone-3-glucuronide (E3G), and luteinizing hormone (LH) in morning urine (EMU) to identify the limits of the fertile phase of the cycle. The start of the fertile phase is pinpointed by the rise in E3G, and the end of the fertile phase by allowing a period for ovum release and survival after detection of the LH surge.(2) “Studies that have investigated the efficacy of the hormonal kit Persona and the Computer thermometers have found that the effectiveness is not as high as the symptothermal double-check method of NFP”.7
(ii) Oestrogen and progesterone metabolites:
Brown’s Ovarian Monitor (developed by Prof Brown, Melbourne) is not generally available in Europe, (1), but it is available in Europe in those Centres who teach the Billings Ovulation Method. It measures the rise in the urine metabolites of oestrogen to mark the beginning of the fertile phase and the rise in progesterone metabolites in urine to mark the end of the fertile phase.3,5
(iii) Measure LH surge :
Home assay kits to measure LH concentration in urine are designed to indicate the time of maximum fertility and are aimed at women who want to conceive, those who may be subfertile or have an unclear mucus symptom. LH kits should not be used by couples who want to avoid pregnancy as they do not predict ovulation sufficiently early to allow for the fertilizing life-span of the sperm in fertile-type mucus, or for the fertilizable life-span of the ovum after ovulation.
Ultrasound:
The development of ultrasound has played an important role in providing basic information on all phases of ovarian activity and is the most accurate method of timing ovulation but is not practical for daily application.6
References:
- Freundl G, Godehardt E, Kern PA, et al; “Estimated maximum failure rates of cycle monitors using daily conception probabilities in the menstrual cycle”; Human Reproduction, (2003), vol 18, no. 12, p2628-2633.
- Bonnar J, Flynn A, Freundl G et al; “Personal hormone monitoring for contraception”; Br J Fam Plann. 1999 Jan 24 (4): 128-134.
- Cavero, C; “Using an ovarian monitor as an adjunct to natural family planning”; Journal of Nurse-Midwifery, vol 40, no 3, May’June 1995; p269-276.
- Guida, M et al; “Efficacy of methods for determining ovulation in a natural family planning program; Fertil & Steril; vol 72, no 5, Nov 1999, p 900-904.
- Blackwell LF, Brown JB, Vigil P et al; “Hormonal monitoring of ovarian activity using the ovarian monitor, Part 1. Validation of home and laboratory results obtained during ovulatory cycles by comparison with radioimmunoassay”; Steroids, 68, (2003), p 465-476.
- Brown JB; ‘Ovarian activity and fertility and the Billings Ovulation Method, 2005; available on the internet if you google Billings ovulation method’
- Frank-Hermann P.et al; ‘The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study'; Human Reproduction; Feb 2007; page 9; p1-10. The study referred to is Freundl G et al (2003) cited as the first reference on this list.
To be most effective, the woman must be taught the symptothermal double-check method of Natural Family Planning by a qualified natural family planning teacher.
